Wiktionary
tetralemma
n. A figure in Ancient Greek and eastern logic with four possibilities.
Wikipedia
Tetralemma
The tetralemma is a figure that features prominently in the logic of India. It states that with reference to any a logical proposition X, there are four possibilities:
X (affirmation) ¬X (negation) X ∧ ¬X (both) equiv. ¬(X ∨ ¬X) (neither)